Polymers for photoreceptor overcoating for use as protective layer against liquid xerographic ink interaction

Abstract

A protective overcoating layer for an electrophotographic imaging device prevents crystallization and leaching of hole transport compounds in a charge transport layer of the imaging device. The overcoat also prevents solvent and ink contact/bending stress charge transport layer cracking. The overcoating layer contains a polyester homopolymer which contains a hole transporting compound and an aliphatic diol in the polymer chain backbone. The homopolymer can be either a meta or para hole transport compound ester linkage polyester homopolymer.

What is claimed is: 
     
       1. An electrophotographic imaging member comprising a charge transport layer and an overcoating layer, said overcoat layer comprising a single component hole transporting polyester homopolymer comprising a hole transport compound and an aliphatic diol in the polymer chain backbone, and wherein said overcoat layer is of a thickness which prevents crystallization and leaching of hole transport compound in said charge transport layer upon exposure to liquid xerographic ink and ink solvent carriers. 
     
     
       2. The electrophotographic imaging member of claim 1 wherein said overcoat layer has a thickness of from about 2 to about 10 micrometers. 
     
     
       3. The electrophotographic imaging member of claim 2 wherein said overcoat layer has a thickness of from about 3 to about 6 micrometers. 
     
     
       4. The electrophotographic imaging member of claim 3 wherein said overcoat layer comprises a meta hole transport compound ester linkage polyester homopolymer having the general molecular formula: ##STR15## 
     
     
       5. The electrophotographic imaging member of claim 4 wherein said polyester homopolymer has 2 to 20 repeating CH 2  units in the chain backbone. 
     
     
       6. The electrophotographic imaging member of claim 5 wherein said polyester homopolymer has the molecular formula: ##STR16## 
     
     
       7. The electrophotographic imaging member of claim 3 wherein said polyester homopolymer overcoat layer comprises a para hole transport compound ester linkage polyester homopolymer having the general molecular formula: ##STR17## 
     
     
       8. The electrophotographic imaging member of claim 7 wherein said polyester homopolymer overcoat has 2 to 20 repeating CH 2  units in the chain backbone. 
     
     
       9. The electrophotographic imaging member of claim 8 wherein said polyester homopolymer has the molecular formula: ##STR18## 
     
     
       10. An electrophotographic imaging member comprising: a supporting substrate;   a charge generating layer;   a charge transport layer; and   an overcoat layer comprising a single component hole transporting polyester homopolymer, wherein said polyester homopolymer comprises a hole transporting compound and an aliphatic diol in the polymer chain backbone, wherein said overcoat layer is of a thickness which prevents crystallization and leaching of hole transport compound in said charge transport layer upon exposure to liquid zerographic ink and ink solvent carriers.   
     
     
       11. The electrophotographic imaging member of claim 10 wherein said overcoat layer has a thickness of from about 2 to about 10 micrometers. 
     
     
       12. The electrophotographic imaging member of claim 11 wherein said overcoat layer has a thickness of from about 3 to about 6 micrometers. 
     
     
       13. The electrophotographic imaging member of claim 12 wherein said polyester homopolymer comprises a meta hole transport compound ester linkage polyester homopolymer having the general molecular formula: ##STR19## 
     
     
       14. The electrophotographic imaging member of claim 13 wherein said polyester homopolymer has 2 to 20 repeating CH 2  units in the chain backbone. 
     
     
       15. The electrophotographic imaging member of claim 14 wherein said polyester homopolymer has the molecular formula: ##STR20## 
     
     
       16. The electrophotographic imaging member of claim 12 wherein said polyester homopolymer comprises a para hole transport compound ester linkage polyester homopolymer having the general molecular formula: ##STR21## 
     
     
       17. The electrophotographic imaging member of claim 16 wherein said polyester homopolymer has 2 to 20 repeating CH 2  units in the chain backbone. 
     
     
       18. The electrophotographic imaging member of claim 17 wherein said polyester homopolymer has the molecular formula: ##STR22## 
     
     
       19. An electrographic imaging member comprising a charge transport layer and an overcoat layer, said overcoat layer comprising a polymer selected from the group consisting of a copolymer of a hole transport compound linked to a urethane, a fluorine-based pendant active moiety functional polymer of a polyester, a fluorine-based pendant active moiety functional polymer of a polycarbonate, a fluorine-based pendant active moiety functional polymer of a polyurethane, and an organo-polyphosphazene having hole transport pendant groups, and wherein said overcoat layer is of a thickness which prevents crystallization and leaching of hole transport compound in said charge transport layer upon exposure to liquid zerographic ink and ink solvent carriers.